function Corr_out = corr_caculate_fu(Corr_in,a0,a)

    Corr_out = a0*Corr_in;

    for i = 1:length(a)

        yanchi = i;
        corr_yuan_zheng = [zeros(1,yanchi),Corr_in(1:end-yanchi)];
        corr_yuan_fu = [Corr_in(yanchi+1:end),ones(1,yanchi)];
        Corr_out = Corr_out + a(i)/2*(corr_yuan_fu+corr_yuan_zheng);

    end

end